Once a Jeev is gone to Dev gathi, it is very difficult for it to come down to earth. Only if the Dev (Jeev) deeply thinks about his previous birth, he will be able to know, but the Das and Dasi would divert their minds to not let them come here. They'd divert by showing them Nataks (Drama). One drama would be for 2000 years. So, even if later they realize and wanna come down, due to passage of so much time, it would be waste to come.